This invention relates to printing devices in typewriters, and particularly to a printing device additionally provided thereon with a printing pressure adjusting mechanism capable of adjusting a printing pressure in accordance with a printing area of the respective letters including signs in a typewriter including a ball-like type head.
Additionally, the aforesaid typewriters include various type typewriters, teletypewriters and other typewriters analogous thereto, and the aforesaid ball-like type heads include not only ordinary spherical type heads but also type heads similar in configuration thereto and cylindrical type heads.
In a typewriter provided thereon with a ball-like type head, positions of the type head in the vertical and turning directions are adapted to be indexed by a letter selecting mechanism so as to print a predetermined letter.
If letters each having a small printing area, such as a period, comma, underline and semicolon, are printed under the same printing pressures as those for other letters each having a comparatively large printing area, then there are possibilities that a typewriter paper and carbon paper are broken, or the letters having a small printing area are printed in more dark color than other letters to be considerably deteriorated in visual appearance. In addition, such disadvantages are presented that ribbons tend to be deformed, so that one ribbon cannot be used for a long period of time, thus requiring frequent changes of ribbons. Consequently, in order to obviate the abovedescribed disadvantages, low printing pressures should be applied to the letters having a small printing area.
In order to achieve this purpose, heretofore, there have been proposed printing pressure adjusting devices. In these conventional devices, when a key lever or a capital-small letter shift lever is pressed, a printing pressure adjusting mechanism is operated, transmitting this operating force to a printing mechanism so as to change the printing pressure in the printing mechanism. This arrangement has necessitated provision of a mechanism for connecting a key lever mechanism to a printing mechanism within the printing pressure adjusting mechanism, thus presenting a disadvantage of complicated construction.